Seat

ABSTRACT

A car seat includes a first heater, a second heater, and a control unit which controls an output to the first heater and an output to the second heater. The control unit executes a temperature-difference adjustment control, in which the output of the second heater is controlled such that the temperature of the bulging portion heated by the second heater with respect to the temperature of the seating surface portion heated by the first heater is made lower when an ambient temperature is a first temperature than when the ambient temperature is a second temperature which is higher than the first temperature.

TECHNICAL FIELD

The present invention relates to a seat of which, a seating surface canbe heated.

BACKGROUND ART

As a seat of which a seating surface can be heated, a seat that includesa plurality of heaters disposed corresponding to each area of contactmade by an occupant seated in the seat (seated person) and a controlsection (controller) which controls a heat generation operation has beendisclosed in Patent Literature 1 for example. The seat in PatentLiterature 1, based on the premise that among the contact parts of ahuman body, there exist parts that feel warmth quickly and having highheating effectiveness to heat supply, while there exists parts that feelwarmth slowly and insensible but once warmed, improve the comfort, isconfigured to heat these two types of parts in order.

CITATION LIST Patent Literatures

Patent Literature 1: Japanese Patent Application Laid-open PublicationNo. 2009-269480

SUMMARY OF THE INVENTION

Incidentally, in the conventional seat, with an object of improving thecomfort, an output of each heater is controlled such that there is nosubstantial temperature difference between areas that are heated by theheaters. However, when a plurality of areas to be heated by the heatersare heated up equally, there would be a problem of an electric powerconsumption becoming large.

The present invention has been made in view of the above-describedcircumstances, and a primary object of the present invention is toprovide a seat which enables to suppress electric power consumptionwhile providing comfort.

To achieve the primary object, the seat of the present inventioncomprises: a first heater which heats up a first area; a second heaterwhich heats up a second area; and a control unit which controls anoutput of the first heater and an output of the second heater inaccordance with an ambient temperature, wherein the control unitexecutes a temperature-difference adjustment control, in which theoutput of the second heater is controlled such that a temperature of thesecond area with respect to a temperature of the first area is madelower when the ambient temperature is a first temperature than when theambient temperature is a second temperature which is higher than thefirst temperature, to thereby increase a difference in temperaturebetween the first area and the second area.

According to such configuration, the output of the second heater iscontrolled such that the temperature of the second area with respect tothe temperature of the first area is made lower when the ambienttemperature is the first temperature (low ambient temperature) than whenthe ambient temperature is the second temperature (high ambienttemperature), and therefore the electric power consumption can besuppressed without giving a feeling of discomfort to the occupant; thisis because when the ambient temperature is the first temperature, evenif the difference between the temperature of the first area and thetemperature of the second area is large, the temperature difference ishard to be sensed by the occupant. Whereas, when the ambient temperatureis the second temperature (high ambient temperature), the temperaturedifference is easy to be sensed by the occupant even if the differencebetween the temperature of the first area and the temperature of thesecond area is not large. However, in this instance, the differencebetween the temperature of the first area and the temperature of thesecond area becomes smaller as compared with the instance in which theambient temperature is the first temperature (low ambient temperature).Therefore, it is possible to secure the comfort.

The above seat may further comprise a temperature sensor which isprovided to an area corresponding to the first heater, and in thetemperature-difference adjustment control, the control unit maycalculate a first required control amount on the basis of a targettemperature and a detected temperature acquired by the temperaturesensor, and control the first heater with the first required controlamount, and calculate a second required control amount on the basis ofthe first required control amount, and control the second heater withthe second required control amount. A magnitude of the second requiredcontrol amount with respect to a magnitude of the first required controlamount nay be smaller when the ambient temperature is the firsttemperature than when the ambient temperature is the second temperature.

With this configuration, it is possible to control the output of thesecond heater such that the temperature of the second area with respectto the temperature of the first area is made lower, with only thetemperature sensor provided to the area corresponding to the firstheater, and to suppress the electric power consumption while providingcomfort.

In the above seat, upon receiving an instruction for heating up theseat, the control unit may supply an electric power only to the firstheater if the detected temperature has not reached a switchingtemperature which is lower than the target temperature.

With this configuration, the first area can be heated up first, so thatif, for example, the first heater is provided to an area where theoccupant can feel the temperature easily, such area can be heated uppromptly to improve the comfort.

In the above seat, the control unit may execute: to calculate anaccumulated electric power consumption obtained by adding an amount ofelectric power outputted to the first heater at every predetermined timeuntil the detected temperature reaches the switching temperature; tosupply a maximum electric power output to the second heater if thedetected temperature has reached the switching temperature, and tosubtract a value obtained by multiplying an amount of electric poweroutputted to the second heater at every predetermined time by atemperature-difference adjustment value that varies according to theambient temperature from the accumulated electric power consumption toobtain a solution; and to execute the temperature-difference adjustmentcontrol if the solution obtained is not higher than a predeterminedvalue. And, the temperature-difference adjustment value may be largerwhen the ambient temperature is the first temperature than when theambient temperature is the second temperature.

With this configuration, after the first area is heated up, the secondarea is heated up promptly to bring the temperature of the second areacloser to the temperature of the first area promptly, thereby improvingthe comfort. Moreover, when the ambient temperature is the firsttemperature (low ambient temperature), the accumulated electric powerconsumption becomes not higher than the predetermined value quickly andthe temperature-difference adjustment control is executed, as comparedwith the case when the ambient temperature is the second temperature(high ambient temperature), so that the time for which the second heateroperates with the maximum output can be shortened. Accordingly, thesecond area is not heated wastefully by the second heater, and theelectric power consumption can be suppressed.

The above seat may further comprise a first sensor which is provided toan area corresponding to the first heater, and a second sensor which isprovided to an area corresponding to the second heater, and in thetemperature-difference adjustment control, the control unit maycalculates a first required control amount on the basis of a firsttarget temperature and a first detected temperature acquired by thefirst temperature sensor, and control the first heater with the firstrequired control amount, and calculate a second required control amounton the basis of a second target temperature and a second detectedtemperature acquired by the second sensor, and control the second heaterwith the second required control amount. A difference between the firsttarget temperature and the second target temperature may be larger whenthe ambient temperature is the first temperature than when the ambienttemperature is the second temperature.

With this configuration, the output of the second heater can becontrolled such that the temperature of the second area with respect tothe temperature of the first area lower is made lower. It is thereforepossible to suppress the electric power consumption while providingcomfort. Moreover, since the temperature sensor is provided to both ofthe area corresponding to the first heater and the area corresponding tothe second heater, it is possible to improve an accuracy of temperaturecontrol, and to improve the comfort.

In the above seat, before executing the temperature-differenceadjustment control, the control unit may supply a maximum electric poweroutput to the second heater if the second detected temperature has notreached a second switching temperature which is lower than the secondtarget temperature.

With this configuration, the second area can be heated up promptly toimprove the comfort.

In the above seat, when the second detected temperature has reached thesecond switching temperature, the control unit may execute thetemperature-difference adjustment control. The second switchingtemperature may be lower when the ambient temperature is the firsttemperature than when the ambient temperature is the second temperature.

With this configuration, when the ambient temperature is the firsttemperature (low ambient temperature), the second detected temperaturereaches the second switching temperature quickly and thetemperature-difference adjustment control is executed, as compared withthe case when the ambient temperature is the second temperature (highambient temperature), so that the time for which the second heateroperates with the maximum output can be shortened. Accordingly, thesecond area is not heated wastefully by the second heater, and theelectric power consumption can be suppressed.

In the above seat, upon receiving an instruction for heating up theseat, the control unit may supply an electric power only to the firstheater if the first detected temperature has not reached a firstswitching temperature which is lower than the first target temperature.

With this configuration, the first area can be heated up first, so thatif, for example, the first heater is provided to an area where theoccupant can feel the temperature easily, such area can be heated uppromptly to improve the comfort.

In the above seat, the first heater may be provided to a seating surfaceportion of the seat, and the second heater may be provided to a bulgingportion which is disposed on left and right outer sides of the seatingsurface portion, and which juts out toward an occupant seated in theseat for supporting a side portion of the occupant.

With this configuration, since the seating surface portion where theoccupant feels the temperature easily can be heated up by the firstheater, it is possible to improve the comfort. On the contrary, for thebulging portion which is disposed farther from the occupant than theseating surface portion, the occupant is not likely to feel discomforteven if there is some temperature difference between the temperature ofthe bulging portion and the temperature of the seating surface portion.Therefore, the electric power consumption can be suppressed furtherwhile suppressing the output of the second heater further.

Herein, the seating surface portion refers to a seating surface portionof a seat cushion or a seat back, and the bulging portion refers to aportion of the seat cushion or the seat back that juts out. The seatingsurface portion of the seat cushion is a portion of the seat cushion onwhich hips and thighs of the occupant rest, more specifically, a portionfor supporting the hips and thighs of the occupant from below. Theseating surface portion of the seat back is a portion of the seat backat which a back of the occupant contacts, more specifically, a portionfor supporting the back of the occupant from behind.

Incidentally, different physiques of occupants sit in the seat; someheaters may contact with the occupant if an occupant with a large bodyframe sits therein, but may not contact with the occupant if an occupantwith a small body frame sits therein. However, the conventionaltechnology does not take into consideration the physique of the occupantseated in the seat, heaters not in contact with the occupant wouldgenerate heat wastefully when an occupant with a small body frame sitsin the seat, which disadvantageously leads to large amount of electricpower consumption.

The present invention has been made in view of the above-describedcircumstances, and a second object of the present invention is toprovide a seat capable of reducing the electric power consumption.

To achieve the second object, the seat may further comprise a physiquedetector which detects a physique of an occupant seated in the seat. Thefirst heater may be a main heater, and the second heater may be asub-heater that is disposed at a position farther from the seatingsurface portion of a seat cushion, than the main heater. And, thecontrol unit may reduce at least a partial output of the sub heater whenthe physique of the occupant detected by the physique detector issmaller than a standard than when the physique of the occupant detectedby the physique detector is not smaller than the standard.

With this configuration, at least a part of the sub-heater disposed at aposition farther from the seating surface portion of the seat cushion,than a position of the main heater, does not contact with the occupantwhen an occupant with a small body frame sits on the seat cushion;therefore, even if the part of the sub-heater is caused to generateheat, it does not contribute so much to the comfort of the occupant. Forthis reason, if the physique of the occupant is smaller than thestandard, at least a partial output of the sub-heater is made lower, sothat a wasteful heat generation by the heater portion not in contactwith the occupant is suppressed, which can reduce the electric powerconsumption.

Herein, the seating surface portion of the seat cushion refers to aportion of the seat cushion on which the hips and thighs of the occupantrest, more specifically, a portion which supports the hips and thighs ofthe occupant from below.

In the above seat, the sub-heater may be disposed on left and rightouter sides of the main heater.

In the above seat, the control unit may stop the electric power supplyto at least a part of the sub-heater if the physique of the occupantdetected by the physique detector is smaller than the standard.

With this configuration, since the electric power supply to the heaterportion not in contact with the occupant is ceased, the electric powerconsumption can be reduced further.

In the above seat, the sub-heater may include a plurality of heaterportions. And, the control unit may control, if the physique of theoccupant detected by the physique detector is smaller than the standard,such that the farther the position of the heater portion from among theplurality of heater portions, disposed from the seating surface portionof a seat cushion, the smaller is the output.

With this configuration, the temperature of the sub-heater can becontrolled to be gradually lowered from the heater portion disposed at aposition closer to the seating surface portion of the seat cushiontoward the heater portion disposed at a position farther from theseating surface portion of the seat cushion, so that increasedtemperature difference between the heater portions can be suppressed.This can improve the comfort of the occupant.

In the above seat, the sub-heater may include: a first heater portion; asecond heater portion which is disposed at a position farther from theseating surface portion of the seat cushion, than a position of thefirst heater portion; and a third heater portion which is disposed at aposition farther from the seating surface portion of the seat cushion,than a position of the second heater portion. And, the control unit maycontrol, if the physique of the occupant detected by the physiquedetector is smaller than the standard, such that an output of thesub-heater is made smaller in order of the first heater portion, thesecond heater portion, and the third heater portion.

With this configuration, the temperature of the sub-heater can becontrolled to be gradually lower toward a direction away from theseating surface portion of the seat cushion, in order of the firstheater portion, the second heater portion, and the third heater portion,so that increased temperature difference between the heater portions canbe suppressed. This can improve the comfort of the occupant.

In the above seat, the sub-heater may be disposed on left and rightsides of the main heater, and the first heater portion, the secondheater portion, and the third heater portion may be disposedside-by-side in this order from an inner side to an outer side in theleftward-rightward direction.

In the above seat, the main heater may include a cushion main-heaterwhich is disposed on the seating surface portion of the seat cushion,and a back main-heater which is disposed on a seating surface portion ofa seat back. And, the sub-heater may include a cushion sub-heater whichis disposed on left and right outer sides of the seating surface portionof the seat cushion, and a back sub-heater which is disposed on left andright outer sides of the seating surface portion of the seat back. Thecontrol unit may stop the electric power supply to the back sub-heaterif the physique of the occupant detected by the physique detector issmaller than a first standard, and stops the electric power supply tothe back sub-heater and the cushion sub-heater if the physique of theoccupant detected by the physique detector is smaller than a secondstandard which is smaller than the first standard.

With this configuration, if the physique of the occupant is smaller thanthe first standard, the electric power supply to the back sub-heater isceased, and if the physique of the occupant is further smaller, theelectric power supply to the back sub-heater and the cushion sub-heateris ceased, so that the electric power consumption can be reduced furtherwhile maintaining the comfort in accordance with the physique of theoccupant.

Herein, the seating surface portion of the seat back refers to a portionof the seat back at which the back of the occupant contacts, morespecifically, a portion for supporting the back of the occupant frombehind.

In the above seat, the main heater may be provided to the seatingsurface portion of the seat, and the sub-heater may be provided to abulging portion which is disposed on left and right outer sides of theseating surface portion, and which juts out toward the occupant forsupporting a side portion of the occupant.

With this configuration, on the one hand, the seating surface portion ofwhich the temperature is felt easily by the occupant can be heated bythe main heater to maintain the comfort. On the other hand, the left andright bulging portions can be heated by the sub heater in accordancewith the physique of the occupant to reduce the electric powerconsumption.

Herein, the seating surface portion of the seat refers to the seatingsurface portion of the seat back or of the seat cushion, and the bulgingportion refers to a bulging portion of the seat back or the seatcushion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a car seat as a seat according to afirst embodiment.

FIG. 2 is a map showing a relationship of accumulated electric powerconsumption and temperature-difference adjustment value in the firstembodiment.

FIG. 3 is a flowchart showing a processing of a control unit in thefirst embodiment.

FIG. 4 includes a graph (a) showing a change in temperature of a seatingsurface portion and a bulging portion when an ambient temperature is afirst temperature, a graph (b) showing an output of a first heater andan output of a second heater, and a graph (c) showing an accumulatedelectric power consumption W, in the first embodiment.

FIG. 5 includes a graph (a) showing a change in temperature of theseating surface portion and the bulging portion when the ambienttemperature is a second temperature which is higher than the firsttemperature, a graph (b) showing an output of the first heater and theoutput of the second heater, and a graph (c) showing the accumulatedelectric power consumption W, in the first embodiment.

FIG. 6 is a perspective view of a car seat as a seat according to asecond embodiment.

FIG. 7 is a map showing a relationship of the difference between firsttarget temperature and second target temperature, with respect toambient temperature, in the second embodiment.

FIG. 8 is a flowchart showing a processing of the control unit in thesecond embodiment.

FIG. 9 includes a graph (a) showing a change in temperature of a seatingsurface portion and a bulging portion when the ambient temperature is afirst temperature, and a graph (b) showing a change in temperature ofthe seating surface portion and the bulging portion when the ambienttemperature is a second temperature which is higher than the firsttemperature, in the second embodiment.

FIG. 10 is a perspective view of a car seat as a seat according to athird embodiment.

FIG. 11 is a table showing output of each heater with respect to weightof an occupant seated in the car seat, in a third embodiment.

FIG. 12 is a flowchart showing a processing of the control unit in thethird embodiment.

FIG. 13 is a perspective view of a car seat as a seat according to afourth embodiment.

FIG. 14 is a map showing an example of a relationship of weight of theoccupant and required control amount, in the fourth embodiment.

FIG. 15 is a flowchart showing a processing of the control unit in thefourth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of a seat according to the present invention will bedescribed below with reference to the accompanying drawings.

First Embodiment

A seat in the present embodiment, as shown in FIG. 1, is configured as acar seat S which is to be mounted in an automobile. This car seat Sincludes a seat cushion S1, a seat back S2, and a headrest S3; the seatcushion S1 is formed by upholstering a pad material made of a cushionmaterial such as urethane foam with a skin material such as syntheticleather and cloth.

The seat cushion S1 includes a seating surface portion S11 which isdisposed at a horizontal center, and which supports hips and thighs ofan occupant seated in the car seat S from below by making a contact, anda bulging portion S12 which is disposed on both left and right outersides of the seating surface portion S11, and which is jutted out towardthe occupant for supporting a side portion of the thighs and hips of theoccupant. Moreover, the seat back S2 also similarly includes a seatingsurface portion S21 which is disposed at a horizontal center, and whichsupports a back of the occupant from behind by making a contact with theback, and a bulging portion S22 which is disposed on both left and rightouter sides of the seating surface portion S21, and which is jutted outtoward the occupant for supporting a side portion of an upper body ofthe occupant.

Center heaters 11 and 12 as a first heater 10 are disposed at an innerside of the skin of the seating surface portion S11 of the seat cushionS1 and at an inner side of the skin of the seating surface portion S21of the seat back S2 respectively. Moreover, side heaters 21 and 22 as asecond heater 20 are disposed at an inner side of the skin of thebulging portion S12 of the seat cushion S1 and the bulging portion S22of the seat back S2 respectively. In other words, in the presentembodiment, the seating surface portions S11 and S21 provided with thefirst heater 10 correspond to a first area that is to be heated by thefirst heater 10, and the bulging portions S12 and S22 provided with thesecond heater 20 correspond to a second area that is to be heated by thesecond heater 20.

In the seating surface portion S21 of the seat back S2, a temperaturesensor 30 is built-in in an area corresponding to the first heater 10,at the inner side of the skin. The temperature sensor 30 is disposed ata position where there is no effect of a body temperature of theoccupant. For example, the temperature sensor 30 may be disposed at alower portion of the seat back S2 and at a rear portion of the seatcushion S1. There is a substantially constant correlation between atemperature detected by the temperature sensor 30 and a temperature of aportion of the seating surface portion S21 with which the occupant makesa contact. A control unit 100 may carry out a control by using thetemperature detected by the temperature sensor 30 as a detectedtemperature, or may carry out a control by estimating the temperature ofthe portion with which the occupant makes a contact on the basis of theabove-described correlation, and letting the temperature estimated to bea detected temperature T.

The control unit 100 is disposed at an appropriate position of the carseat S. The temperature sensor 30 is connected to the control unit 100to output a signal of the detected temperature T to the control unit100. Moreover, the first heater 10 and the second heater 20 areconnected to the control unit 100. Furthermore, the control unit 100 isconfigured such that an electric power is supplied to the control unit100 from a power-supply unit 90 which is driven by a battery mounted ina vehicle, and the control unit 100 controls an output of the firstheater 10 and an output of the second heater 20 on the basis of thedetected temperature T acquired from the temperature sensor 30. In thepresent embodiment, the power-supply unit 90 is configured to supply theelectric power within a range of a predetermined upper-limit output forthe first heater 10 and the second heater 20 of the car seat S, and asan example, an upper limit is let to be 100 W.

The control unit 100 is connected to an operation switch of a heatermounted in the vehicle, and controls the first heater 10 and the secondheater 20 upon receiving an instruction for heating the car seat S fromthe operation switch. The control unit 100 is configured to execute afirst stage of raising promptly a temperature of the seating surfaceportions S11 and S21 with which the occupant makes a contact, by heatingthe first heater 10 intensively during a heating period of raising thedetected temperature T toward a target temperature T12 upon receivingthe instruction for heating from the operation switch, a second stage ofstarting the heating of the second heater 20 and bringing a temperatureof the bulging portions S12 and S22 closer to the temperature of theseating surface portions S11 and S21, and a third stage of adjusting thedetected temperature T to the target temperature T12 after thetemperature of the bulging portions S12 and S22 has risen to someextent.

During the warm season, and in cases such as when the heater has beenused once before the operation of the operation switch, sometimes thedetected temperature T may be higher than the target temperature T12already, when the instruction for heating has been received by theoperation switch. In that case, the control unit 100, without executingthe control of the so-called heating period here, carries out a controlsimilar to the third stage.

The control unit 100, as a standard for switching from the first stageto the second stage, makes a judgment of whether or not the detectedtemperature T has reached a switching temperature T11 which is lowerthan the target temperature T12. In the first stage in which thedetected temperature T has not reached the switching temperature T11,the control unit 100 supplies the electric power only to the firstheater 10, and without supplying the electric power to the second heater20, controls the first heater 10 by a 100% first output proportion.

In the present embodiment, a proportion of the output of the firstheater 10 with respect to the maximum output is referred to as a firstoutput proportion, and a proportion of the output of the second heater20 with respect to the maximum output is referred to as a second outputproportion. Moreover, to make the description easily understandable,when the maximum output of the first heater 10 and the maximum output ofthe second heater 20 are exemplified, the maximum output of the firstheater 10 is let to be 100 W which is same as a total of the maximumpermissible output (100 W) of the first heater 10 and the second heater20, and the maximum output of the second heater is let to be 50 W. Inother words, in a case of the first heater 10 outputting with 100% inthe first stage, the electric power of 100 W is to be supplied.

Moreover, the control unit 100 does not return the processing to thefirst stage after the processing advanced to the second stage upon thedetected temperature T once reaching the switching temperature T11.Therefore, if the detected temperature T has reached the switchingtemperature T11, the control unit 100 sets a flag F to 1, indicatingthat the detected temperature T has reached the switching temperatureT11. An initial value of the flag F is 0, and when the electric power isceased to be supplied to the control unit 100 in a case such as when theoperation switch has been switched OFF, the flag F is reset to 0.

The control unit 100, in the second stage after the detected temperatureT has reached the switching temperature T11, lets the second outputproportion to be 100% in order to bring the temperature of the bulgingportions S12 and S22 closer to the temperature of the seating surfaceportions S11 and S21 by using fully the capacity of the second heater20, and lets the first output proportion to be an appropriate valuewithin the range of the maximum permissible output. Consequently, thecontrol unit 100, in the second stage, supplies the electric power tothe second heater 20 with the maximum output, which is 100% secondoutput proportion. In other words, the control unit 100 supplies theelectric power of 50 W to the second heater 20. On the other hand, forcontrolling the first heater 10, the control unit 100 calculates a firstrequired control amount mv1 on the basis of the target temperature T12and the detected temperature T acquired by the temperature sensor 30. Itis possible to calculate the first required control amount mv1 bymv1=Kp×e+ie/Ki, as a required control amount of a so-called PI controlfor example.

Here, e is a difference between the target temperature T12 and thedetected temperature T, Kp is a proportional control constant, ie is anintegral (addition) of e in a predetermined period in the past, and Kiis an integral control constant. The constants Kp and Ki are set to besuch that the first required control amount mv1 can be used as aninstruction value of the output (a value that instructs the first outputproportion and the second output proportion) in the third stage afterthe detected temperature T has come closer to the target temperatureT12. Moreover, the detected temperature T and the target temperatureT12, for the purpose of calculation here, may not be necessarily inunits such as “° C.”, and may be a numerical value of a voltage outputfrom the temperature sensor 30. It is preferable to adjust the constantsKp and Ki appropriately according to a scale of these values oftemperature. The value mv1, according to the calculation, sometimessurpasses 100 as a result of the large difference e between the targettemperature T12 and the detected temperature T in the first stage andthe second stage (namely, state of heating with the as large output aspossible). Since the electric power of a value of the output proportion(0%˜100%) is supplied to the first heater 10 and the second heater 20,in order that mv1 assumes a numerical value not higher than 100, whenmv1 surpasses 100, it is let to be 100. In other words, mv1 iscalculated in a range below 100 which is an upper limit value.

In the second stage, since the electric power of 50 W is supplied to thesecond heater 20, of the maximum permissible output 100 W, the remainderis 50 W. Therefore, in the second stage, since it is necessary tocontrol the first heater at not more than 50 W, if the first requiredcontrol amount mv1 that has been calculated is larger than 50, thecontrol unit 100 controls the first heater 10 by 50 W, or in otherwords, controls with 50% first output proportion, and if the firstrequired control amount mv1 is not more than 50, the control unit 100controls the first heater 10 letting the first required control amountmv1 that has been calculated to be the first output proportion.Accordingly, the first heater 10 is controlled by the output proportionnot more than 50% in the second stage.

The switching from the second stage to the third stage is carried outwhen the temperature of the bulging portions S12 and S22 has come closerto certain extent to the temperature of the seating surface portions S11and S21. In the present embodiment, one temperature sensor 30 being onlyprovided to the seating surface portion S21, the control unit 100presumes that the temperature of bulging portions S12 and S22 has comecloser to the temperature of the seating surface portions S11 and S21 onthe basis of an amount of heat supplied to seating surface portions S11and S12 by the first heater 10 from the start of heating, or in otherwords, on the basis of the accumulated electric power consumption.

Here, for example, when a thermal capacity of the seating surfaceportions S11 and S21 and a thermal capacity of the bulging portions S12and S22 are same, temperatures of both portions at the time of start ofheating are same, and the total amount of heat supplied to the seatingsurface portions S11 and S21 and the bulging portions S12 and S22 issame, the temperature of both the portions should rise up to almost sametemperature. As a matter of course, the temperature of the portion forwhich the heating was started earlier, being high for a long time, anamount of heat released becomes large, and therefore, although thetemperature does not match precisely, if an amount of heat to besupplied is adjusted on the basis of a test result of heating, it ispossible to adjust to a temperature of almost the same level. Similarlyfor a difference in the thermal capacity of the seating surface portionsS11 and S21 and the bulging portions S12 and S22, by adjusting theamount of heat to be supplied on the basis of a test result of heating,it is possible to adjust to an equal temperature even if the electricpower is supplied to the first heater 10 in advance. Moreover, usingsuch tendency, by adjusting the amount of heat to be supplied to thesecond heater 20 for example, it is also possible to provide a desiredtemperature difference between the seating surface portions S11 and S21,and the bulging portions S11 and S21.

In the present embodiment, the control unit 100 sums up values in whichan amount of the electric power (watts) outputted to the first heater 10is multiplied by a predetermined first coefficient A1 for apredetermined time such as for each cycle of control (such as 10 m sec)for example, letting the accumulated electric power consumption to be W.In other words, till the detected temperature T reaches the switchingtemperature T11, in the first stage of making the first heater 10 outputwith 100% (100 W), the control unit 100 calculates the accumulatedelectric power consumption W by W=W+100×A1.

Moreover, in the second stage, since the control unit 100 controls thefirst heater 10 by 50 W (50%) or letting a value of the first requiredcontrol amount mv1 to be the first output proportion, the control unit100 adds the accumulated electric power consumption W to 50×A1 or mv1×A1for each control cycle. On the other hand, the control unit 100, in thesecond stage, subtracts from the accumulated electric power consumption,a value obtained by multiplying the amount of electric power supplied tothe second heater 20 by a second coefficient 2 and atemperature-difference adjustment value A3 which varies according to atemperature of the environment (ambient temperature) in which the carseat S is disposed. In other words, in the second stage, since thesecond heater 20 is controlled by 50 W which is the maximum output ofthe second heater 20, value 50×A2×A3 is subtracted from the accumulatedelectric power consumption W.

Moreover, when the accumulated electric power consumption W becomes notmore than a predetermined value such as 0, the control unit 100terminates the second stage, then shifts the processing to the thirdstage, and executes a temperature-difference adjustment control whichwill be described later.

In the present embodiment, the second coefficient A2 is larger than thefirst coefficient A1, and as an example, the first coefficient A1 is0.01 and the second coefficient A2 is 0.04.

Moreover, the temperature-difference adjustment value A3, as an example,can be calculated by A3=a1×W1+b1. Here, W1 is an accumulated electricpower consumption when the detected temperature T has reached theswitching temperature T11. As shown in FIG. 2, thetemperature-difference adjustment value A3 has been set such that as W1becomes larger, the value becomes larger.

Here, as shown in FIG. 4 (a) and FIG. 5 (a), it takes a longer time forthe detected temperature T to reach a first switching temperature T11after the electric power is supplied to the first heater 10, when theambient temperature (here, corresponds to the detected temperature Tbefore heating the car seat S) is a first temperature T1 (low ambienttemperature) than when the ambient temperature is a second temperatureT2 which is higher than the first temperature T1. Consequently, sincethe electric power supplied to the first heater 10 becomes large and theaccumulated electric power consumption W becomes large, and also W1which is the accumulated electric power consumption when the detectedtemperature T1 reached the switching temperature T11, thetemperature-difference adjustment value A3 becomes larger when theambient temperature is the first temperature T1 than when the ambienttemperature is the second temperature T2. Moreover, as a result, thevalue 50×A2×A3 also becomes a large value when the ambient temperatureis low. Accordingly, in the second stage, if the ambient temperature islow, since 50×A2×A3 which becomes a large value is to be subtracted fromthe accumulated electric power consumption W, the accumulated electricpower consumption W rapidly becomes a value not higher than apredetermined value, and the processing moves rapidly to the thirdstage.

In the third stage, the control unit 100 executes atemperature-difference adjustment control in which a difference betweenthe temperature of the seating surface portions S11 and S21 and thetemperature of the bulging portions S12 and S22 is made larger bycontrolling the output of the second heater 20 to lower the temperatureof the bulging portions S12 and S22 with respect to the temperature ofthe seating surface portions S11 and S21, when the ambient temperatureis the first temperature T1 (low ambient temperature) than when theambient temperature is the second temperature T2 (high ambienttemperature). More specifically, in the present embodiment, the controlunit 100, in the temperature-difference adjustment control, controls thefirst heater 10 by the first required control amount mv1 calculated onthe basis of the target temperature T12 and the detected temperature T,and calculates a second required control amount mv2 on the basis of thefirst required control amount mv1, and controls the heater 20 by thesecond required control amount mv2. It is possible to calculate thesecond required control amount mv2 by mv2=mv1/A3.

Here, since the temperature-difference adjustment value A3 becomeslarger when the ambient temperature is the first temperature T1 thanwhen the ambient temperature is the second temperature T2, a magnitudemv2/mv1 of the second required control amount mv2 with respect to thefirst required control amount mv1 becomes smaller when the ambienttemperature is the first temperature T1 than when the ambienttemperature is the second temperature T2. Consequently, in the thirdstage, since an amount of heat supplied to the second heater 20 withrespect to the amount of heat supplied to the first heater 10 becomessmaller when the ambient temperature is the first temperature T1 thanwhen the ambient temperature is the second temperature T2, thetemperature of the bulging portions S12 and S22 with respect to thetemperature of the seating surface portions S11 and S21 becomes lower,and the difference in the temperature of the seating surface portion S11and S21 and the temperature of the bulging portions S12 and S22 becomeslarger.

A processing of the control unit 100 in the above-described car seat Swill be described below with reference to FIG. 3. The control unit 100repeatedly carries out a processing from a start to an end shown in FIG.3 for each control cycle.

The control unit 100, to start with, makes a judgment of whether or notan instruction for heating by a heater has been received, and if thereis no instruction (No at step S101), terminates the processing.

On the other hand, when there is an instruction for heating by theheater (Yes at step S101), the control unit 100 acquires the detectedtemperature T from the temperature sensor 30 (step S102), and calculatesthe first required control amount mv1 (step S103). Moreover, the controlunit 100 makes a judgment of whether the flag F is 1, and if the flag Fis not 1 (No at step S104), the process advances to step S110, and ifthe flag F is 1 (Yes at step S104), the process advances to step S114without making a judgment of whether or not to enter the first stage.

At step S110, the control unit 100 makes a judgment of whether or notthe detected temperature T is higher than or equal to the switchingtemperature T11, and if the detected temperature T is not higher than orequal to the switching temperature T11 (No at step S110), as the firststage, the control unit 100 makes the heater 10 output with 100%, or inother words, 100 W (step S111), and calculates the accumulated electricpower consumption W by W=W+100×A1 (step S112), and terminates theprocessing.

On the other hand, if the detected temperature T is higher than or equalto the switching temperature T11 (Yes at step S110), the control unit100 sets the flag F to 1 (step S113), and moreover, calculates thetemperature-difference adjustment value A3 by A3=a1×W1+b1 (step S114).Furthermore, the control unit 100 makes a judgment of whether or not theaccumulated electric power consumption W is lower than or equal to 0(step S120).

If the accumulated electric power consumption W is not lower than orequal to 0, (No at step S120), the processing being in the second stage,the control unit 100 makes a judgment of whether or not the firstrequired control amount mv1 is larger than 50. If the first requiredcontrol amount mv1 is larger than 50 which is the upper limit value (Yesat step S121), the control unit 100 makes the first heater 10 outputwith 50% (50 W), and makes the second heater 20 output with 100% (50 W)(step S122). Moreover, the control unit 100 calculates the accumulatedelectric power consumption W by W=W+50×A1−50×A2×A3 (step S123), andterminates the processing.

On the other hand, if the first required control amount mv1 is notlarger than 50 which is the upper limit value (No at step S121), thecontrol unit 100 makes the first heater 10 output with mv1 (less than 50W. becomes 100 W×mv1), and makes the second heater 20 output with 100%(50 W) (step S124). Moreover, the control unit 100 calculates theaccumulated electric power consumption W by W=W+mv1×A1−50×A2×A3 (stepS125), and terminates the processing.

At step S120, if the accumulated electric power consumption W lower thanor equal to 0 (Yes at step S120), this being the third stage, thecontrol unit 100 calculates the second required control amount mv2 bymv2=mv1/A3 (step S131), and controls the first heater 10 with the firstrequired control amount mv1, and controls the second heater 20 with thesecond required control amount mv2 (step S132), and terminates theprocessing.

When the above-described processing is carried out, as the occupantoperates the operation switch and starts heating the car seat S, theoutput of the first heater 10 and the output of the second heater 20,and the temperature of the seating surface portions S11 and S21 and thetemperature of the bulging portions S12 and S22 change as shown in FIGS.4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b). More specifically, in thefirst stage till times t11 and t21, the entire 100 W which is themaximum permissible output, is used by the first heater 10, and thetemperature of the seating surface portions S11 and S21 is heated asquickly as possible. Accordingly, with a firm contact with the occupant,by warming up a portion from a lumbar region up to a back where theoccupant feels the temperature easily, it is possible to give theoccupant a comfortable seating feeling. The temperature of the bulgingportions S12 and S22 has risen till the times t11 and t21 because theseat is warmed up by receiving heat of the occupant.

Moreover, in the first stage, the accumulated electric power consumptionW is obtained by adding the electric power outputted to the first heater10 as shown in FIG. 4 (c) and FIG. 5 (c).

At the times t11 and t21, as the detected temperature T detected by thetemperature sensor 30 reaches the switching temperature T11, theprocessing shifts to the second stage. In the second stage, as shown inFIG. 4 (b) and FIG. 5 (b), the control unit 100 supplies the electricpower with the maximum output 50 W (100%) to the second heater, andsupplies the remaining 50 W electric power to the first heater 10.Moreover, at the times t12 and t22, as the detected temperature T nearsthe target temperature T12, since mv1 becomes 50 or less than 50 as aresult of the difference e becoming small, the control unit 100 controlsthe first heater 10 by the first required control amount mv1 (electricpower not more than 50 W) which is a value lower than or equal to 50.

In the second stage (times t11 to t13, and time t21 to t23), theaccumulated electric power consumption W goes on becoming smaller by anamount equivalent to the electric power supplied to the second heater 20as shown in FIG. 4 (c) and FIG. 5 (c).

Moreover, at the times t13 and t23, as the accumulated electric powerconsumption W becomes less than or equal to 0, the processing shifts tothe third stage. In the present embodiment, the accumulated electricpower consumption obtained when the detected temperature T has reachedthe switching temperature T11 is larger and the temperature-differenceadjustment value A3 becomes a larger value (see FIG. 2), when theambient temperature is the first temperature T1 which is low shown inFIG. 4 than when the ambient temperature is the second temperature T2which is higher than the first temperature T1 shown in FIG. 5.Accordingly, the value (50×A2×A3) to be subtracted from the accumulatedelectric power consumption W becomes larger, and a reduction gradient ofthe accumulated electric power consumption W shown at the times t11 tot13 in FIG. 4 (c) has become larger as compared to a reduction gradientshown at the times t21 to t23 in FIG. 5(c). Consequently, when theambient temperature is the first temperature T1 which is low, theaccumulated electric power consumption W decreases more quickly andbecomes lower than or equal to 0 more quickly as compared to the case inwhich the accumulated electric power consumption W has decreased with agentle reduction gradient as shown in FIG. 5(c) supposedly. Therefore,it is possible to terminate rapidly the second stage of supplying theelectric power to the second heater 20 with the maximum output.Moreover, accordingly, before executing the temperature-differenceadjustment control in the third stage, it is possible to make thedifference in the temperature of the seating surface portions S11 andS21 and the temperature of the bulging portions S12 and S22 larger ascompared to the case in which the ambient temperature is the secondtemperature T.

In the third stage, the control unit 100 controls the first heater 10 bythe first required control amount mv1, and controls the second heater 20by the second required control amount mv2 (=mv1/A3). At this time, whenthe ambient temperature is the first temperature T1, thetemperature-difference adjustment value A3 is larger as compared to thecase in which the ambient temperature is the second temperature T2, sothat the magnitude mv2/mv1 of the second required control amount mv2with respect to the first required control amount mv1 becomes small.Accordingly, the proportion of the output of the second heater 20 withrespect to the output of the first heater 10 becomes smaller when theambient temperature is the first temperature T1 shown in FIG. 4(b) thanwhen the ambient temperature is the second temperature T2 shown in FIG.5(b), and the amount of heat supplied by the second heater 20 withrespect to the amount of heat supplied by the first heater 10 becomessmaller. This makes it possible to maintain a state in which thedifference in the temperature of the seating surface portions S11 andS21 and the temperature of the bulging portions S12 and S22 is largerwhen the ambient temperature is the first temperature T1 than when theambient temperature is the second temperature 2, because the temperatureof the bulging portions S12 and S22 with respect to the temperature ofthe seating surface portions S11 and S21 becomes low.

According to the car seat S as described above in the presentembodiment, it is possible to suppress the electric power consumptionwhile providing the comfort. More specifically, it was revealed from theresult of the study that, when the ambient temperature is the firsttemperature T1, even if the difference in the temperature of the seatingsurface portions S11 and S21 and the temperature of the bulging portionsS12 and S22 is made large, the occupant hardly feels the difference inthe temperatures. For this reason, it is possible to suppress theelectric power consumption without giving discomfort to the occupant, bycontrolling the output of the second heater 20 to lower the temperatureof the bulging portions S12 and S22 with respect to the temperature ofthe seating surface portions S11 and S21 when the ambient temperature isthe first temperature T1 than when the ambient temperature is the secondtemperature T2. On the other hand, when the ambient temperature is thesecond temperature T2 which is high, it was revealed that even when thedifference in the temperature of the seating surface portions S11 andS21 and the temperature of the bulging portions S12 and S22 is notlarge, the difference in the temperatures is easily felt by theoccupant. In this case, the difference in the temperature of the seatingsurface portions S11 and S21 and the temperature of the bulging portionsS22 becomes smaller as compare to the case in which the ambienttemperature is the first temperature T1 which is low, and thus it ispossible to secure the comfort.

Moreover, according to the present embodiment, in thetemperature-difference adjustment control, the control unit 100 controlsthe first heater 10 by the first required control amount mv1 calculatedon the basis of the detected temperature T and the target temperatureT12, then calculates the second required control amount mv2 whichbecomes a small value when the ambient temperature is low, on the basisof the first required control amount mv1, and controls the second heater20 by the second required control amount mv2. Therefore, it is possibleto control the output of the second heater 20 to lower the temperatureof the bulging portions S12 and S22 with respect to the temperature ofthe seating surface portions S11 and S21, only with temperature sensor30.

Moreover, the control unit 100 firstly supplies the electric power onlyto the first heater 10 if the detected temperature T has not reached theswitching temperature T11 when the instruction for heating the car seatS has been received, so that it is possible to heat up promptly theseating surface portions S11 and S21 of which the temperature is felteasily by the occupant. This can improve the comfort.

Moreover, according to the present embodiment, the control unit 100supplies the maximum electric power output to the second heater 20 whenthe detected temperature T has reached the switching temperature T11.Accordingly, it is possible to bring the temperature of the bulgingportions S12 and S22 closer to the temperature of the seating surfaceportions S11 and S21 by heating promptly the bulging portion S12 and S22after the seating surface portions S11 and S21 have been heated. Thismakes it possible to improve the comfort. Furthermore, the control unit100 subtracts the temperature-difference adjustment value A3 whichbecomes a large value when the ambient temperature is low, from theaccumulated electric power consumption W, and if the accumulatedelectric power consumption W becomes a value smaller than or equal to apredetermined value, the control unit 100 executes thetemperature-difference adjustment control. Accordingly, the accumulatedelectric power consumption W becomes lower than or equal to 0 morerapidly to execute the temperature-difference adjustment control whenthe ambient temperature is the first temperature T1 which is low thanwhen the ambient temperature is the second temperature T2 which is high.Accordingly, it is possible to shorten the time for which the secondheater 20 operates with the maximum output and to minimize the wastefulheating of the bulging portions S12 and S22 by the second heater 20.This makes it possible to suppress the electric power consumption.

Moreover, since the first heater 10 is provided to the seating surfaceportions S11 and S21, it is possible to heat by the first heater 10 theseating surface portions S11 and S21 of which the temperature is felteasily by the occupant. This makes it possible to improve the comfort.Moreover, regarding the bulging portions S12 and S22 that is disposedfarther from the occupant than the seating surface portions S11 and S21,a temperature difference to certain extent with the seating surfaceportions S11 and S21 hardly gives any feeling of discomfort to theoccupant, so that providing the second heater 20 to the bulging portionsS12 and S22 makes it possible to suppress further the electric powerconsumption by suppressing further the output of the second heater 20.

Second Embodiment

A seat according to the present embodiment is configured as a car seat Sto be mounted in a car. This car seat S includes the seat cushion S1,the seat back S2, and the headrest S3. In this embodiment, partsdifferent from those described in the first embodiment will be describedin detail, and same reference numerals will be assigned to componentswhich are similar as in the first embodiment, and the descriptionthereof will be omitted.

In the seating surface portion S21 of the seat back S2, a firsttemperature sensor 30A is built-in in an area corresponding to the firstheater 10, at the inner side of the skin, and in the bulging portionS22, a second temperature sensor 30B is built-in in an areacorresponding to the second heater 20, at the inner side of the skin.The temperature sensors 30A and 30B, similar to the temperature sensor30 of the first embodiment, are disposed at positions where there is noeffect of the body temperature of the occupant,

The first temperature sensor 30A is connected to the control unit 100,to output a signal of a first detected temperature Ta to the controlunit, and the second temperature sensor 30B is connected to the controlunit 100, to output a signal of a second detected temperature Tb to thecontrol unit 100. Moreover, an ambient-temperature sensor 30 as a thirdtemperature sensor which detects the ambient temperature, or morespecifically, a temperature of an interior of vehicle, is connected tothe control unit 100. The ambient-temperature sensor 30C outputs asignal of an ambient temperature Tc to the control unit 100. Theambient-temperature sensor 30C may be built-in in the car seat S,similarly as the temperature sensors 30A and 30B, or may be a sensorthat has been provided separately in addition to the car seat S, such asa room-temperature sensor provided to a car originally. In other words,the ambient temperature Tc may be acquired from a sensor provided in thecar seat S, or may be acquired from a sensor provided outside the carseat S.

The control unit 100 receives an instruction for heating the car seat Sfrom the operation switch, and controls the first heater 10 and thesecond heater 20. The control unit 100 is configured to execute thefirst stage of raising promptly the temperature of the seating surfaceportions S11 and S21 by making the first heater 10 heat intensively uponreceiving the instruction for seat heating from the operation switch,the second stage of starting the heating of the second heater 20 andbringing the temperature of the bulging portions S12 and S22 closer tothe temperature of the seating surface portions S11 and S21, and thethird stage of adjusting the detected temperatures Ta and Tb to targettemperatures T12 and T22.

As a standard for switching from the first stage to the second stage,the control unit 100 makes a judgment of whether or not the firstdetected temperature Ta acquired by the first temperature sensor 30A hasreached a first switching temperature T11 which is lower than the targettemperature T12. In the first stage in which the first detectedtemperature Ta has not reached the first switching temperature T11, thecontrol unit 100 supplies the electric power only to the first heater10, and without supplying the electric power to the second heater 20,controls the first heater 10 with the maximum output.

When the first detected temperature Ta has reached the first switchingtemperature T11, the control unit 100 sets the flag F to 1 indicatingthat the first detected temperature Ta has reached the first switchingtemperature T11.

As a standard for switching from the second stage to the third stage,the control unit 100 makes a judgment of whether or not the seconddetected temperature Tb acquired by the second temperature sensor 30Bhas reached a second switching temperature T21 which is lower than thesecond target temperature T22. In the stage 2 (before executing thetemperature-difference adjustment control) in which the second detectedtemperature Tb has not reached the second switching temperature T21, thecontrol unit 100 supplies the maximum electric power output to thesecond heater 20. Moreover, in the second stage, the control unit 100calculates the first required control amount mv1 on the basis of thefirst target temperature T12 and the first detected temperature Ta, andcontrols the first heater 10 by the first required control amount mv1.For instance, the first required control amount mv1 can be calculated bymv1=Kp×e+ie/Ki, as the required control amount of the PI controlsimilarly as in the case of the first embodiment.

When the second detected temperature Tb has reached the second switchingtemperature T21, the control unit 100 sets the flag F to 2 indicatingthat the second detected temperature Tb has reached the second switchingtemperature T21. The initial value of the flag F is 0, and when theoperation switch is switched OFF, the flag F is reset to 0.

When the second detected temperature Tb has reached the second switchingtemperature T21, the control unit 100 terminates the second stage andshifts to the third stage, and then executes the temperature-differenceadjustment control.

In the third stage, the control unit 100 executes thetemperature-difference adjustment control in which a difference betweenthe temperature of the seating surface portions S11 and S21 and thetemperature of the bulging portions S12 and S22 is made larger bycontrolling the output of the second heater 20 to lower the temperatureof the bulging portions S12 and S22 with respect to the temperature ofthe seating surface portions S11 and S21 when the ambient temperature Tcis the first temperature T1 than when the ambient temperature Tc is thesecond temperature T2 which is higher than the first temperature T1.More specifically, according to the present embodiment, in thetemperature-difference adjustment control, the control unit 100 controlsthe first heater 10 by the first required control amount mv1 calculatedon the basis of the first target temperature T12 and the first detectedtemperature Ta, and calculates the second required control amount mv2 onthe basis of the second target temperature T22 and the second detectedtemperature Tb, and controls the heater 20 by the second requiredcontrol amount mv2. The second required control amount mv2 can becalculated as a required control amount of the PI control, similarly asthe first required control amount mv1 for example.

The second target temperature T22 can be calculated byT22=T12−(−a2×Tc+b2), as an example, on the basis of the first targettemperature T12 and the ambient temperature Tc. As shown in FIG. 7, adifference (T12−T22) between the first target temperature T12 and thesecond target temperature T22 is set such that the value becomes largerwhen the ambient temperature Tc is the first temperature T1 than whenthe ambient temperature Tc is the second temperature T2 which is higherthan the first temperature T1. Consequently, a value −a2×Tc+b2 becomeslarger when the ambient temperature Tc is the first temperature T1 thanwhen the ambient temperature Tc is the second temperature T2, andtherefore, the second target temperature T22 calculated byT12−(−a2×Tc+b2) becomes a small value.

Moreover, the second switching temperature T21 as a standard forswitching from the second stage to the third stage has been set to be alower value when the ambient temperature Tc is the first temperature T1than when the ambient temperature Tc is the second temperature T2. As anexample, the second switching temperature T21 can be calculated byT21=T22−Td. Accordingly, the second switching temperature T21 becomes alow value when the ambient temperature Tc is low and the second targettemperature T22 becomes a small value, and becomes a high value when theambient temperature Tc is high and the second target temperature T22becomes a large value. Here, Td may be a constant or may be a variable.

A processing of the control unit 100 in the above-described car seat Swill be described below with reference to FIG. 8. The control unit 100repeatedly carries out a processing from a start to an end shown in FIG.8 for each control cycle.

The control unit 100, to start with, makes a judgment of whether or notan instruction for heating by a heater has been received, and terminatesthe processing if it receives no instruction (No at step S201).

On the other hand, if there is an instruction for heating by the heater(Yes at step S201), the control unit 100 acquires the detectedtemperatures Ta, Tb, and Tc from the temperature sensors 30A, 30B, and30C (step S202), and calculates each of the second target temperatureT22 and the second switching temperature T21 (step S203). Moreover, thecontrol unit 100 makes a judgment of whether the Flag F is 1 or higherthan 1 (1 or 2), and if the flag F is not 1 or higher than 1 (i.e., theflag F is 0) (No at step S204), the processing advances to step S210,and if the flag F is 1 or higher than 1 (Yes at step S204), theprocessing advances to step S215.

At step S210, the control unit 100 makes a judgment of whether or notthe first detected temperature Ta of the first temperature sensor 30A isnot lower than the first switching temperature T11, and if the firstdetected temperature Ta is lower than the first switching temperatureT11 (No at step S210), being the first stage, the control unit 100 makesthe first heater 10 output with 100% (step S211), and terminates theprocessing.

On the other hand, if the first detected temperature Ta is higher thanor equal to the first switching temperature T11 (Yes at step S210), thecontrol unit 100 sets the flag F to 1 (step S214). Moreover, the controlunit 100 makes a judgment of whether the flag F is 2, and if the flag Fis not 2 (No at step S215), the processing advances to step S220, and ifthe flag F is 2 (Yes at step S215), the processing advances to stepS231.

At step S220, the control unit 100 makes a judgment of whether or notthe second detected temperature Tb of the second temperature sensor 30Bis higher than or equal to the second switching temperature T21, and ifthe second detected temperature Tb is not higher than or equal to thesecond switching temperature T21 (No at step S220), being the secondstage, the control unit 100 calculates the first required control amountmv1 (step S221), and makes the first heater 10 output with mv1, andmakes the second heater 20 output with 100% (step S22), and terminatesthe processing.

On the other hand, if the second detected temperature Tb is higher thanor equal to the second switching temperature T21 (Yes at step S220), thecontrol unit 100 sets the flag F to 2 (step S223). Moreover, being thethird stage, the control unit 100 calculates each of the first requiredcontrol amount mv1 and the second required control amount mv2 (stepS231), and makes the first heater 10 output with mv1 and the secondheater 20 output with mv2 (step S232), and terminates the processing.

According to the processing as described above, when the occupantoperates the operation switch and starts heating the car seat S, thecontrol unit 100, in the first stage from a time t31 up to a time t41,supplies the maximum electric power output to the first heater 10, andheats up the temperature of the seating surface portions S11 and S21promptly.

Moreover, at the times t31 and t41, if the first detected temperature Tadetected by the first temperature sensor 30A reaches the first switchingtemperature T11, the processing shifts to the second stage.

In the second stage, the control unit 100 supplies the maximum electricpower output to the second heater 20, and control the first heater 10 bythe first required control amount mv1. Moreover, at times t32 and t42,if the second detected temperature Tb detected by the second sensor 30Breaches the second switching temperature T21, the processing shifts tothe third stage. According to the present embodiment, the secondswitching temperature T21 is lower when the ambient temperature Tc isthe first temperature T1 which is low as shown in FIG. 9 (a) than whenthe ambient temperature Tc is the second temperature T2 which is higherthan the first temperature T1 as shown in FIG. 9 (b). Accordingly, thesecond detected temperature Tb reaches the second switching temperatureT21 rapidly, and it is possible to terminate rapidly the second stage ofsupplying the maximum electric power output to the second heater 20.This makes it possible, before executing the temperature-differenceadjustment control in the third stage, to make the difference betweenthe temperature of the seating surface portions S11 and S21 and thetemperature of the bulging portions S12 and S22 larger as compared tothe case in which the ambient temperature Tc is the second temperatureT2.

In the third stage, the control unit 100 controls the first heater 10 bythe first required control amount mv1 and controls the second heater 20by the second required control amount mv2. At this time, the differencein the first target temperature T12 and the second target temperatureT22 becomes larger, more specifically, the second target temperature T22becomes smaller with respect to the first target temperature T12 whenthe ambient temperature Tc is the first temperature T1 than when theambient temperature Tc is the second temperature T2. Consequently, sincethe magnitude mv2/mv1 of the second required control amount mv2 withrespect to the first required control amount mv1 becomes small, anamount of heat supplied to the second heater 20 with respect to anamount of heat supplied to the first heater 10 becomes smaller.Accordingly, since the temperature of the bulging portions S12 and S22with respect to the temperature of the seating surface portions S11 andS21 becomes lower, the difference in the temperature of the seatingsurface portions S11 and S21 and the temperature of the bulging portionsS12 and S22 can be maintained to be larger when the ambient temperatureTc is the first temperature T1 than when the ambient temperature Tc isthe second temperature T2.

According to the car seat S as described above in the presentembodiment, the electric power consumption can be suppressed whileproviding the comfort similarly as in the first embodiment.

Moreover, according to the present embodiment, in thetemperature-difference adjustment control, the control unit 100 controlsthe first heater 10 by the first required control amount mv1 calculatedon the basis of the first target temperature T12 and the first detectedtemperature Ta, and controls the second heater 20 by the second requiredcontrol amount mv2 that is calculated on the basis of the second targettemperature T22 which differs to a large extent from the first targettemperature T12 when the ambient temperature Tc is low, and the seconddetected temperature Tb. Accordingly, it is possible to control theoutput of the second heater 20 to lower the temperature of the bulgingportions S12 and S22 with respect to the temperature of the seatingsurface portions S11 and S21. Moreover, the first temperature sensor 30Afor acquiring the first detected temperature Ta is provided in an areacorresponding to the first heater 10 and the second temperature sensor30B for acquiring the second detected temperature Tb is provide in anarea corresponding to the second heater 20, so that the accuracy oftemperature control can be improved by the two temperature sensors 30Aand 30B to improve the comfort.

Moreover, in the present embodiment, before executing thetemperature-difference adjustment control, the control unit 100 suppliesthe maximum electric power output to the second heater 20 when thesecond detected temperature Tb has not reached the second switchingtemperature T21. This can heat the bulging portions S12 and S22promptly, and bring the temperature of the bulging portions S12 and S22closer to the temperature of the seating surface portions S11 and S21promptly, to improve the comfort.

Moreover, in the present embodiment, the control unit 100 executes thetemperature-difference adjustment control when the second detectedtemperature Tb has reached the second switching temperature T21 whichassumes a low value if the ambient temperature Tc is low. Therefore, thesecond detected temperature Tb reaches the second switching temperatureT21 faster when the ambient temperature Tc is the first temperature T1(lower ambient temperature) than when the ambient temperature Tc is thesecond temperature T2 (higher ambient temperature), and thetemperature-difference adjustment control can be executed quickly.Accordingly, the time for which the second heater 20 operates with themaximum output is shortened, and the bulging portions S12 and S22 arenot heated wastefully by the second heater 20, so that the electricpower consumption can be suppressed.

Moreover, the control unit 100 supplies the electric power only to thefirst heater 10 when the first detected temperature Ta has not reachedthe first switching temperature T11 upon receiving the instruction forheating the car seat S. This makes it possible to firstly heat theseating surface portions S11 and S21 promptly of which the temperatureis felt easily by the occupant, and to improve the comfort.

Although various embodiments of the present invention have beendescribed above, the present invention is not limited to theseembodiments, and changes or modifications may be made to the structurethereof where appropriate.

For instance, in the first embodiment, although the second requiredcontrol amount mv2 is calculated by multiplying the first requiredcontrol amount mv1 by a reciprocal of the temperature-differenceadjustment value A3, the method of calculation is not limited to thisspecific calculation. The second required control amount, for example,may be calculated from a map or a formula indicating a relationship ofthe first required control amount and the second required control amountthat is set in advance on the basis of the results of the heating test.

Moreover, assuming that the ambient temperature varies with the elapsingof time, the temperature-difference adjustment value A3 may be varied onthe basis of the ambient temperature, and the output of the secondheater in the third stage may be changed according to the ambienttemperature. For example, when the ambient temperature becomes high, thetime till the detected temperature T becomes higher than or equal to theswitching temperature T11 becomes short. Accordingly, thetemperature-difference adjustment value A3 may be varied as a functionof time on the basis of this time. Moreover, the ambient temperature maybe detected, and the temperature-difference adjustment value A3 may bevaried as a function of the ambient temperature, on the basis of theambient temperature detected.

In the above-described embodiments, although the first heater 10 isprovided to the seating surface portions S11 and S21, and the secondheater 20 is provided to the bulging portions S12 and S22, thearrangement of the first heater and the second heater is not limited tothis specific arrangement. For example, the first heater may be providedto the seat cushion and the second heater may be provided to the seatback. Moreover, both of the first heater and the second heater may beprovided to the seating surface portions, or may be provided to thebulging portions.

In the above-described embodiments, although an independent type seatthat is to be used for a driver's seat and a front passenger seat of anautomobile has been exemplified as the car seat S, the seat is notlimited to this specific type, and may be a bench type seat that iscommonly used for a backseat of an automobile. Moreover, in theabove-described embodiments, although the car seat S that is mounted ina car has been exemplified as a seat, the seat may be a vehicle seat tobe mounted in a railway car, a marine vessel, and an aircraft.Furthermore, the seat is not limited to a vehicle seat, and may be aseat used in a house for example.

In the above-described embodiments, although the seat has aconfiguration such that the electric power is supplied from thepower-supply unit 90 that is driven by the battery mounted in thevehicle, the present invention is not limited to this specificconfiguration. For instance, the battery may be mounted in the seat.Further, if the seat is a seat intended for home use, the electric powermay be supplied from a commercial power supply.

A seat according to a third embodiment and a seat according to a fourthembodiment of the present invention will be described below withreference to FIG. 10 to FIG. 15.

The seat according to the third embodiment and the seat according to thefourth embodiment are seats in which the electric power consumption of aplurality of heaters is adjusted according to the physique of theoccupant. The seat according to the third embodiment and the seataccording to the fourth embodiment may be used in combination with theabove-described seat according to the first embodiment or the seataccording to the second embodiment.

Third Embodiment

As shown in FIG. 10, a seat according to the present embodiment isconfigured as a car seat S mounted in a car. This car seat S includesthe seat cushion S1, the seat back S2, and the headrest S3; the seatcushion S1 is formed by upholstering a pad material made of a cushionmaterial such as urethane foam with a skin material such as syntheticleather and cloth. Further, the car seat S includes a main heater 10 asa first heater, a sub-heater 20 as a second heater, a seat-weight sensor40 as an example of a physique detecting unit, and the control unit 100.

The seat cushion S1 includes the seating surface portion S11 which isdisposed at a horizontal center, and which supports the hips and thighsof the occupant from below by making a contact, and the bulging portionS12 which is disposed on each of left and right outer sides of theseating surface portion S11, and which is jutted out toward the occupantfor supporting the side portions of the thighs and hips of the occupant.The seat back S2 also includes the seating surface portion S21 which isdisposed at a horizontal center, and which supports the back of theoccupant from behind by making a contact with the back, and the bulgingportion S22 which is disposed on each of left and right outer sides ofthe seating surface portion S21, and which is jutted out toward theoccupant for supporting the side portions of the upper body of theoccupant.

The main heater 10 is a heater in the form of a sheet provided to theseating surface portions S11 and S21 of the car seat S, and includes acushion main-heater (center heater) 11 and a back main-heater (centerheater) 12. The cushion main-heater 11 is disposed between the padmaterial and the skin material of the seating surface portion S11 of theseat cushion S1, and the back main-heater 12 is disposed between the padmaterial and the skin material of the seating surface portion S21 of theseat back S2.

The sub-heater 20 is a heater in the form of a sheet provided to thebulging portions S12 and S22 of the car seat S, and includes a cushionsub-heater (side heater) 21 and a back sub-heater (side heater) 22. Thecushion sub-heater 21 is disposed between the pad material and the skinmaterial of the bulging portion S12 provided on the left and right outersides of the seating surface portion S11, and the back sub-heater 22 isdisposed between the pad material and the skin material of the bulgingportion S22 provided on the left and right outer sides of the seatingsurface portion S21. Moreover, the cushion sub-heater 21 is disposed onthe left and right outer sides of the cushion main-heater 11, and theback sub-heater 22 is disposed on the left and right outer sides of theback main-heater 12.

By this arrangement of the heaters 10 and 20, in the present embodiment,the cushion sub-heater 21 is disposed at a position farther from theseating surface portion S11 of the seat cushion S1, than the cushionmain-heater 11, and the back sub-heater 22 is disposed at a positionfarther from the seating surface portion S21 of the seat back S2, thanthe back main-heater 12. Moreover, the back sub-heater 22 is disposed ata position farther from the seating surface portion S11 of the seatcushion S1, than the back main-heater 12.

The cushion main heater 11 and the back main-heater 12 which constitutethe main heater 10, and the left and right cushion sub-heaters 21 andthe left and right back sub-heaters 22 which constitute the sub-heater20 are respectively connected to the control unit 100.

The seat-weight sensor 40 is a sensor which detects the physique of theoccupant sitting in the car seat S, more specifically, a weight (bodyweight) of the occupant. The seat-weight sensor 40 is disposed under theseat cushion S1. The seat-weight sensor 40 is connected to the controlunit 100 to output a signal of the weight (hereinafter, referred to as“occupant's weight”) WT of the occupant to the control unit 100.

The control unit 100 is a unit which controls an output of the mainheater 10 and an output of the sub-heater 20, and is disposed at anappropriate position of the car seat S. The control unit 100 may bedisposed outside the car seat S. The control unit 100 is configured suchthat the electric power is supplied from the power-supply unit 90 whichis driven by the battery mounted in the vehicle, and controls the outputof the main heater 10 and the output of the sub-heater 20 by theelectric power supplied.

The operation switch (not shown) provided to the vehicle is connected tothe control unit 100. Upon receiving an instruction for heating with theheaters from the operation switch, the control unit 100 controls theoutput of the main heater 10 and the output of the sub-heater 20 on thebasis of information of the physique of the occupant detected by theseat-weight sensor 40, or in other words, the occupant's weight WT. Morespecifically, the control unit 100 makes at least a part of the outputof the sub-heater 20 smaller when the occupant's weight WT is smallerthan a standard than when the occupant's weight WT is more than or equalto the standard.

To be more specific, as shown in FIG. 11, the control unit 100 puts allthe heaters, more specifically, the main heater 10 (the cushionmain-heater 11 and the back main-heater 12), the left and right cushionsub-heaters 21, and the left and right back sub-heaters 22 in an ONstate of supplying the electric power, if the occupant's weight WT ismore than or equal to a second weight threshold value WT2 as an exampleof a first standard. This causes all the heaters to generate heat.

Further, the control unit 100 puts the main heater 10 and the left andright cushion sub-heaters 21 in the ON state in which the electric poweris supplied, and on the other hand, puts the left and right backsub-heater 22 in an OFF state in which the electric power is notsupplied, if the occupant's weight WT is smaller than the second weightthreshold value WT2, and is more than or equal to a first weightthreshold value WT1 as an example of a second standard which is smallerthan the second weight threshold value WT2. Accordingly, the main heater10 and the left and right cushion sub heaters 21 generate heat. In otherwords, if the occupant's weight WT is smaller than the second weightthreshold value WT2 as the first standard, the control unit 100 stopsthe electric power supply (lets the output to be 0) to the backsub-heater 22, and reduces a partial output of the sub heater 20.

Further, the control unit 100 puts the main heater 10 in the ON state inwhich the electric power is supplied, and on the other hand, puts theleft and right cushion sub-heaters 21 and the left and right backsub-heaters 22 in the OFF state in which the electric power is notsupplied, if the occupant's weight WT is smaller than the first weightthreshold value WT1, and more than or equal to a seating judgmentthreshold value WT0. Accordingly, the main heater 10 produces heat. Inother words, if the occupant's weight WT is smaller than the firstweight threshold value WT1 as the second standard, the control unit 100stops the electric power supply to the back sub-heater 22 and thecushion sub-heater 21 (lets the output to be 0), and reduces the outputof the overall sub-heater 20.

If the occupant's weight WT is smaller than the seating judgmentthreshold value WT0, the control unit 100 puts all the heaters in theOFF state in which no electric power is supplied. Accordingly, theheaters do not generate heat even when the operation switch is operated.

The second weight threshold value WT2 can be set in consideration of abody weight of an occupant who has a physique such that his/her bodycontacts all the heaters including the cushion main-heater 11, the backmain-heater 12, the left and right cushion sub-heaters 21, and the leftand right back sub-heaters 22, when he/she sits in the car seat S.Further, the first weight threshold value WT1 can be set inconsideration of a body weight of an occupant who has a physique suchthat his/her body mainly contacts only with the cushion main-heater 11and the back main-heater 12, when he/she sits in the car seat S.

The seating judgment threshold value WT0 can be set appropriately as avalue smaller than the first weight threshold value WT1. For example,the seating judgment threshold value WT0 can be set as a weight formaking a judgment that an occupant is not sitting in the car seat S oralternatively as a weight such that when an infant sits in the car seatS, the heater does not operate.

A processing of the control unit 100 in the car seat S as describedabove will be described below with reference to FIG. 12.

The control unit 100 repeatedly carries out a processing from a start toan end shown in FIG. 12 for each control cycle.

The control unit 100, to start with, makes a judgment of whether or notan instruction for heating by a heater has been received (step S301). Ifthere is no instruction for heating (No at step S301), the control unit100 terminates the processing. On the other hand, if there is aninstruction for heating (Yes at step S301), the control unit 100acquires the occupant's weight WT from the seat-weight sensor 40 (stepS302), and makes a judgment of whether or not the occupant's weight WTis more than or equal to the seating judgment threshold value WT0 (stepS303).

If the occupant's weight WT is smaller than the seating judgmentthreshold value WT0 (No at step S303), the control unit 100 puts all theheaters in the OFF state (step S304), and terminates the processing.

If the occupant's weight WT is not smaller than the seating judgmentthreshold value WT0 (Yes at step S303), the control unit 100 makes ajudgment of whether or not the occupant's weight WT is more than orequal to the first weight threshold value WT1 (step S310).

If the occupant's weight WT is smaller than the first weight thresholdvalue (No at step S310), the control unit 100 puts the main heater 10 inthe ON state, and puts the sub-heater 20 (cushion sub-heater 21 and theback sub-heater 22) in the OFF state (step S311), and terminates theprocessing.

If the occupant's weight WT is more than or equal to the first weightthreshold value WT1 (Yes at step S310), the control unit 100 makes ajudgment of whether or not the occupant's weight WT is more than orequal to the second weight threshold value WT2 (step S320).

If the occupant's weight WT is smaller than the second weight thresholdvalue WT2 (No at step S320), the control unit 100 puts the main heater10 and the cushion sub-heater 21 in the ON state, and puts the backsub-heater 22 in the OFF state (step S321), and terminates theprocessing.

If the occupant's weight WT is more than or equal to the second weightthreshold value WT2 (Yes at step S320), the control unit 100 puts themain heater 10 and the sub-hear 20 (cushion sub-heater 21 and the backsub-heater 22) in the ON state (step S322), and terminates theprocessing.

According to the car seat S as described above in the presentembodiment, at least a part of the sub-heater 20 disposed at theposition farther from the seating surface portion S11 of the seatcushion S1, than the main heater 10 does not contact the occupant whenan occupant with a small body frame sits on the seat cushion S1.Therefore, it does not contribute much to the comfort of the occupant,even if the sub-heater 20 is made to generate heat. Accordingly, if thebody frame of the occupant (occupant's weight WT) is smaller than thestandard, at least a partial output of the sub-heater 20 is made lower,so that a wasteful heat generation by the heater portion not in contactwith the occupant is suppressed. This can reduce the electric powerconsumption in the car seat S.

Moreover, in the present embodiment, if the occupant's weight WT issmaller than the standard, since the electric power supply to at least apart of the sub-heater 20 is stopped, the electric power supply to aheater portion not in contact with the occupant is ceased, and theoutput thereof becomes 0. Accordingly, the electric power consumption inthe car seat S can be made smaller as compared to the case in which theoutput of at least a part of the sub-heater 20 is halved for example.

Moreover, in the present embodiment, if the occupant's weight WT issmaller than the second weight threshold value WT2, the electric powersupply to the back sub-heater 22 is ceased, and if the body frame of theoccupant is further smaller (i.e., the occupant's weight WT is smallerthan the first weight threshold value WT1), the electric power supply tothe back sub-heater 22 and the cushion sub-heater 21 is ceased.Accordingly, the electric power consumption can be reduced further whilemaintaining the comfort in accordance with the physique of the occupant.

Moreover, the main heater 10 is provided to the seating surface portionsS11 and S21, and the sub-heater 20 is provided to the bulging portionsS12 and S22. With this configuration, on the one hand, the seatingsurface portions S11 and S21 of which the temperature is felt easily bythe occupant can be heated by the main heater 10 to maintain thecomfort. On the other hand, the left and right bulging portions S12 andS22 can be heated by the sub heater 20 in accordance with the physiqueof the occupant to reduce the electric power consumption.

Fourth Embodiment

As shown in FIG. 13, a seat according to the present embodiment isconfigured as a car seat S mounted in a car, and includes the seatcushion S1, the seat back S2, and the headrest S3. Further, the car seatS includes the main heater 10, the sub-heater 20, the seat-weight sensor40, and the control unit 100. In this embodiment, parts different fromthose described in the third embodiment will be described in detail, andsame reference numerals will be assigned to components which are similaras in the third embodiment, and the description thereof will be omitted.

The cushion sub-heater 21 and the back sub-heater 22 include a pluralityof heater portions that are controllable individually. Morespecifically, the cushion sub-heater 21 includes a first heater portion21A, a second heater portion 21B, and a third heater portion 21C, andthe back sub-heater 22 includes a first heater portion 22A, a secondheater portion 22B, and a third heater portion 22C.

The first heater portion 21A is disposed one each on both left side andright side of the cushion main-heater 11, the second heater portion 21Bis disposed one each on left and right outer sides of each first heaterportion 21A, and the third heater portion 21C is disposed one each onleft and right outer sides of each second heater portion 21B. Similarly,the first heater portion 22A is disposed one each on both left side andright side of the back main-heater 12, the second heater portion 22B isdisposed one each on left and right outer sides of each first heaterportion 22A, and the third heater portion 22C is disposed one each onleft and right outer sides of each second heater portion 22B. In otherwords, the first heater portion 21A, the second heater portion 21B, andthe third heater portion 21C, and the first heater portion 22A, thesecond heater portion 22B, and the third heater portion 22C are disposedside-by-side in order from an inner side toward an outer side in aleftward-rightward direction.

By this arrangement, in the present embodiment, the second heaterportion 21B is disposed at a position farther from the seating surfaceportion S11 of the seat cushion S1, than the first heater portion 21A,and the third heater portion 21C is disposed at a position farther fromthe seating surface portion S11, than the second heater portion 21B.Moreover, the second heater portion 22B is disposed at a positionfarther from the seating surface portion S21 of the seat back S2, thanthe first heater portion 22A, and the third heater portion 22C isdisposed at a position farther from the seating surface portion S21,than the second heater portion 22B. Furthermore, the second heaterportion 22B is disposed at a position farther from the seating surfaceportion S11 of the seat cushion S1, than the first heater portion 22A,and the third heater portion 22C is disposed at a position farther fromthe seating surface portion S11, than the second heater portion 22B.

Each of the first heater portion 21A, the second heater portion 21B, andthe third heater portion 21C of the cushion sub-heater 21, and the firstheater portion 22A, the second heater portion 22B, and the third heaterportion 22C of the back sub-heater 22 is connected to the control unit100.

Upon receiving an instruction for heating with the heater from theoperation switch (not shown), the control unit 100 controls the outputof the main heater 10 and the output of the sub-heater 20 on the basisof the occupant's weight WT. More specifically, if the occupant's weightWT is smaller than the standard, the control unit 100 makes the outputsmaller in order of the heater portion disposed farthest from theseating surface portion S11 from among the plurality of heater portionsof the sub-heater 20, or in order of the first heater portions 21A and22A, the second heater portions 21B and 22B, and the third heaterportions 21C and 22C.

More specifically, the control unit 100 calculates a required controlamount mcv for each heater from the occupant's weight WT, and makes eachheater output with the required control amount mcv calculated. To bemore specific, the control unit 100 calculates each of a requiredcontrol amount mcv1 for the main heater 10 (the cushion main-heater 11and the back main-heater 12), a required control amount mcv2 for thefirst heater portions 21A and 22A, a required control amount mcv3 forthe second heater portions 21B and 22B, and a required control amountmcv4 for the third heater portions 21C and 22C, and makes the mainheater 10, the first heater portions 21A and 22A, the second heaterportions 21B and 22B, and the third heater portions 21C and 22C outputwith the required control amounts mcv1, mcv2, mcv3, and mcv4respectively.

Each of the required control amounts mcv1, mcv2, mcv3, and mcv4 can becalculated by the following expressions (1) to (4) as an example.

mcv1=WT×a1+b1   (1)

mcv2=WT×a2+b2   (2)

mcv3=WT×a3+b3   (3)

mcv4=WT×a4+b4   (4)

In expressions (1) to (4), gradients a1 to a4, and intercepts b1 to b4have been set in advance by experiment and simulation.

As shown in FIG. 14, expression (1) which calculates the requiredcontrol amount mcv1 of the main heater 10 has been set as a value whichdoes not vary that significantly even when the occupant's weight WTvaries. Accordingly, by making the main heater 10 output with therequired control amount mcv1, the control unit 100 does not let theoutput of the main heater 10 to vary substantially even when theoccupant's weight WT varies.

On the other hand, expression (2) which calculates the required controlamount mcv2 of the first heater portions 21A and 22A has been set as avalue such that when the occupant's weight WT becomes smaller, therequired control amount becomes smaller as compared to the case ofexpression (1). Accordingly, by making the first heater portions 21A and22A output with the required control amount mcv2, the control unit 100makes the output of the first heater portions 21A and 22A smaller indirect proportion to the occupant's weight WT as compared to the case ofthe main heater 10.

Moreover, expression (3) which calculates the required control amountmcv3 of the second heaters 21B and 22B have been set as a value suchthat the required control amount becomes smaller than the amount inexpression (2) when the occupant's weight WT becomes smaller.Accordingly, by making the second heater portions 21B and 22B outputwith the required control amount mcv3, the control unit 100 makes theoutput of the second heater portions 21B and 22B smaller in directproportion to the occupant's weight WT as compared to the case of thefirst heater portions 21A and 22A.

Moreover, expression (4) which calculates the required control amountmcv4 of the third heater portions 21C and 22C has been set as a valuesuch that the required control amount becomes smaller than the amount inexpression (3) when the occupant's weight WT becomes smaller.Accordingly, by making the third heater portions 21C and 22C output withthe required control amount mcv4, the control unit 100 makes the outputof the third heater portions 21C and 22C smaller in direct proportion tothe occupant's weight WT as compared to the case of the second heaterportions 21B and 22B.

A processing of the control unit 10 in the above-described car seat Swill be described below with reference to FIG. 15.

The control unit 100 repeatedly carries out a processing from a start toan end shown in FIG. 15 for each control cycle.

The control unit 100, to start with, makes a judgment of whether or notan instruction for heating by a heater has been received (step S401). Ifthere is no instruction for heating by a heater (No at step S401), thecontrol unit 100 terminates the processing. On the other hand, if thereis an instruction for heating by the heater (Yes at step S401), thecontrol unit 100 acquires the occupant's weight WT from the seat-weightsensor 40 (step S402), and makes a judgment of whether or not theoccupant's weight WT is more than or equal to the seating judgmentthreshold value WT0 (step S403).

If the occupant's weight WT is smaller than the seating judgmentthreshold value WT0 (No at step S403), the control unit 100 puts all theheaters in the OFF state (step S404), and terminates the processing.

If the occupant's weight WT is more than or equal to the seatingjudgment threshold value WT0 (Yes at step S403), the control unit 100calculates each of the required control amount mcv1 of the main heater10, the required control amount mcv2 of the first heater portions 21Aand 22A, the required control amount mcv3 of the second heater portions21B and 22B, and the required control amount mcv4 of the third heaterportions 21C and 22C (step S405). Moreover, the control unit 100 makesthe main heater 10 output with the required control amount mcv1, makesthe first heater portions 21A and 22A output with the required controlamount mcv2, makes the second heater portions 21B and 22B output withthe required control amount mcv3, and makes the third heater portions21C and 22C with the required control amount mcv4 (step S406), andterminates the processing.

According to the processing as described above, as shown in FIG. 14, ifan occupant with a large body frame (refer to an occupant's weight WTL)whose body contacts all of the main heater 10, the first heater portions21A and 22A, the second heater portions 21B and 22B, and the thirdheater portions 21C and 22C of the sub-heater 20 sits in the car seat S,the output of each heater (required control amount mcv) becomes almostthe same, and the heaters are warmed up substantially uniformly, tothereby secure the comfort. On the other hand, if an occupant with asmall body frame (refer to an occupant's weight WTS) whose body contactsthe main heater 10 but less likely contacts other heater portionsgradually in order of the first heater portions 21A and 22A, the secondheater portions 21B and 22B, and the third heater portions 21C and 22Csits in the car seat S, the output of each heater (required controlamount mcv) becomes smaller gradually in order of the first heaterportions 21A and 22A, the second heater portions 21B and 22B, and thethird heater portions 21C and 22C. This makes it possible to make theelectrical power consumption small while securing the comfort.

According to the car seat S as described above in the presentembodiment, similarly as in the third embodiment, the wastefulgeneration of heat by the heater portion not in contact with theoccupant with a small body frame can be suppressed, so that the electricpower consumption in the car seat S can be reduced.

Further, in the present embodiment, the temperature of the sub-heater 20can be controlled to be gradually lowered from the heater portiondisposed at a position closer to the seating surface portion S11 of theseat cushion S1 toward the heater portion disposed at a position fartherfrom the seating surface portion S11 of the seat cushion S1, or morespecifically, in order of the first heater portions 21A and 22A, thesecond heater portions 21B and 22B, and the third heater portions 21Cand 22C, so that increased temperature difference between the heaterportions can be suppressed. This can improve the comfort of theoccupant.

The third embodiment and the fourth embodiment of the present inventionhave been described above. However, the present invention is not limitedto the embodiments as described above, and changes or modifications maybe made to the structure thereof where appropriate.

For example, in the third embodiment, the output of the sub-heater 20 is0 if the occupant's weight WT is smaller than the standard. However, thepresent invention is not limited to this specific control, and theoutput of the sub-heater may be made smaller in proportion to theoccupant's weight becoming smaller. Further, in the fourth embodiment,the output of the sub-heater 20 is made smaller gradually in the orderof the first heater portions 21A and 22A, the second heater portions 21Band 22B, and the third heater portions 21C and 22C. However, the presentinvention is not limited to this specific control, and the output of thesub-heater may be made 0 gradually in order of the third heaterportions, the second heater portions, and the first heater portions asthe occupant's weight becomes smaller.

In the fourth embodiment, the plurality of heater portions (the firstheater portions 21A and 22A, the second heater portions 21B and 22B, andthe third heater portions 21C and 22C) of the sub-heater 20 are disposedside-by-side in the leftward-rightward direction. However, the presentinvention is not limited to this specific arrangement. For example, theplurality of heater portions of the sub-heater may be disposedside-by-side in a frontward-rearward direction of the seat cushion, ormay be disposed one above another in a vertical direction of the seatback. Moreover, the plurality of heater portions of the sub-heater arenot limited to the three heater portions consisting of the first heaterportions, the second heater portions, and the third heater portions, andmay be two, or may be four or more than four.

In the third embodiment and the fourth embodiment, the main heater 10 isprovided to the seating surface portions S11 and S21, and the sub-heater20 is provided to the bulging portions S12 and S22. However, the presentinvention is not limited to this specific arrangement. For example, boththe main heater and the sub-heater may be provided to the seatingsurface portion, or both the main heater and the sub-heater may beprovided to the bulging portion. Moreover, the main heater may beprovided to the seating surface portion of the seat cushion, and thesub-heater may be provided to the bulging portion of the seat cushion,and to the seating surface portion and the bulging portion of the seatback.

Further, in the third embodiment and the fourth embodiment, the subheater 20 is disposed on each of left and right outer sides of the mainheater 10. However, the present invention is not limited to thisspecific arrangement. For example, the sub-heater may be provided onlyone of the left and right sides of the main heater. Moreover, thesub-heater and the main heater may be disposed one behind another in thefrontward-rearward direction in the seat cushion, or may be disposed oneabove another in the vertical direction in the seat back.

In the third embodiment and the fourth embodiment, the seat-weightsensor 40 has been exemplified as the physique detecting unit. However,the physique detecting unit is not limited to this specific sensor. Forexample, the physique detecting unit may be a pressure sensor. In thiscase, the pressure sensor may be disposed on the seating surface portionand the bulging portion of the seat, and a sub-heater may be provided toa seating surface portion and a bulging portion of the seatcorresponding to the pressure sensor, so that if there is an instructionfor heating by a heater, for example, the control unit 100 puts thesub-heater corresponding to the pressure sensor that has detected anoccupant, in the ON state in which the electric power is supplied, andputs the sub-heater corresponding to the pressure sensor that does notdetect an occupant, in the OFF state in which no electric power issupplied. Accordingly, the output of at least a part of the sub-heatercan be reduced. Moreover, the physique detecting unit may be a camerathat captures an occupant sitting in the car seat. In this case, thephysique of the occupant is judged from an image or a moving image ofthe occupant acquired by the camera, and the output of the sub-heater iscontrolled on the basis of this judgment result. The judgment of thephysique of the occupant may be made by a control unit provided with afunction section for a physique judgment or by a judging unit to beprovided separately from the control unit.

In the third embodiment and the fourth embodiment, although anindependent type seat that is to be used for a driver's seat and a frontpassenger seat of an automobile has been exemplified as the car seat S,the seat is not limited to this specific type, and may be a bench typeseat that is commonly used for a backseat of an automobile. Moreover, inthe third embodiment and the fourth embodiment, although the car seat Sthat is mounted in a car has been exemplified as a seat, the seat may bea vehicle seat to be mounted in a railway car, a marine vessel, and anaircraft. Furthermore, the seat is not limited to a vehicle seat, andmay be a seat used in a house for example.

In the third embodiment and the fourth embodiment, although the seat hasa configuration such that the electric power is supplied from thepower-supply unit 90 that is driven by the battery mounted in thevehicle, the present invention is not limited to this specificconfiguration. For instance, the battery may be mounted in the seat.Further, if the seat is a seat intended for home use, the electric powermay be supplied from a commercial power supply.

Each of the elements explained in the above-described embodiments andmodified embodiments may be optionally combined.

1. A seat comprising: a first heater which heats up a first area; asecond heater which heats up a second area; and a control unit whichcontrols an output of the first heater and an output of the secondheater in accordance with an ambient temperature, wherein the controlunit executes a temperature-difference adjustment control, in which theoutput of the second heater is controlled such that a temperature of thesecond area with respect to a temperature of the first area is madelower when the ambient temperature is a first temperature than when theambient temperature is a second temperature which is higher than thefirst temperature, to thereby increase a difference in temperaturebetween the first area and the second area.
 2. The seat according toclaim 1, further comprising a temperature sensor which is provided to anarea corresponding to the first heater, wherein the control unit, in thetemperature-difference adjustment control, calculates a first requiredcontrol amount on the basis of a target temperature and a detectedtemperature acquired by the temperature sensor, and controls the firstheater with the first required control amount, and calculates a secondrequired control amount on the basis of the first required controlamount, and controls the second heater with the second required controlamount, and wherein a magnitude of the second required control amountwith respect to a magnitude of the first required control amount issmaller when the ambient temperature is the first temperature than whenthe ambient temperature is the second temperature.
 3. The seat accordingto claim 2, wherein the control unit, upon receiving an instruction forheating up the seat, supplies an electric power only to the first heaterif the detected temperature has not reached a switching temperaturewhich is lower than the target temperature.
 4. The seat according toclaim 3, wherein the control unit executes: to calculate an accumulatedelectric power consumption obtained by adding an amount of electricpower outputted to the first heater at every predetermined time untilthe detected temperature reaches the switching temperature; to supply amaximum electric power output to the second heater if the detectedtemperature has reached the switching temperature, and to subtract avalue obtained by multiplying an amount of electric power outputted tothe second heater at every predetermined time by atemperature-difference adjustment value that varies according to theambient temperature from the accumulated electric power consumption toobtain a solution; and to execute the temperature-difference adjustmentcontrol if the solution obtained is not higher than a predeterminedvalue, wherein the temperature-difference adjustment value is largerwhen the ambient temperature is the first temperature than when theambient temperature is the second temperature.
 5. The seat according toclaim 1, further comprising a first sensor which is provided to an areacorresponding to the first heater, and a second sensor which is providedto an area corresponding to the second heater, wherein the control unit,in the temperature-difference adjustment control, calculates a firstrequired control amount on the basis of a first target temperature and afirst detected temperature acquired by the first temperature sensor, andcontrols the first heater with the first required control amount, andcalculates a second required control amount on the basis of a secondtarget temperature and a second detected temperature acquired by thesecond sensor, and controls the second heater with the second requiredcontrol amount, and wherein a difference between the first targettemperature and the second target temperature is larger when the ambienttemperature is the first temperature than when the ambient temperatureis the second temperature.
 6. The seat according to claim 5, wherein thecontrol unit, before executing the temperature-difference adjustmentcontrol, supplies a maximum electric power output to the second heaterif the second detected temperature has not reached a second switchingtemperature which is lower than the second target temperature.
 7. Theseat according to claim 6, wherein when the second detected temperaturehas reached the second switching temperature, the control unit executesthe temperature-difference adjustment control, and wherein the secondswitching temperature is lower when the ambient temperature is the firsttemperature than when the ambient temperature is the second temperature.8. The seat according to claim 5, wherein the control unit, uponreceiving an instruction for heating up the seat, supplies an electricpower only to the first heater if the first detected temperature has notreached a first switching temperature which is lower than the firsttarget temperature.
 9. The seat according to claim 1, wherein the firstheater is provided to a seating surface portion of the seat, and whereinthe second heater is provided to a bulging portion which is disposed onleft and right outer sides of the seating surface portion, and whichjuts out toward an occupant seated in the seat for supporting a sideportion of the occupant.
 10. The seat according to claim 1, furthercomprising a physique detector which detects a physique of an occupantseated in the seat, wherein the first heater is a main heater, and thesecond heater is a sub-heater that is disposed at a position fartherfrom the seating surface portion of a seat cushion, than the mainheater, and wherein the control unit reduces at least a partial outputof the sub heater when the physique of the occupant detected by thephysique detector is smaller than a standard than when the physique ofthe occupant detected by the physique detector is not smaller than thestandard.
 11. The seat according to claim 10, wherein the sub-heater isdisposed on left and right outer sides of the main heater.
 12. The seataccording to claim 10, wherein the control unit stops the electric powersupply to at least a part of the sub-heater if the physique of theoccupant detected by the physique detector is smaller than the standard.13. The seat according to claim 10, wherein the sub-heater includes aplurality of heater portions, and wherein the control unit controls, ifthe physique of the occupant detected by the physique detector issmaller than the standard, such that the farther the position of theheater portion from among the plurality of heater portions, disposedfrom the seating surface portion of a seat cushion, the smaller is theoutput.
 14. The seat according to claim 10, wherein the sub-heaterincludes: a first heater portion; a second heater portion which isdisposed at a position farther from the seating surface portion of theseat cushion, than a position of the first heater portion; and a thirdheater portion which is disposed at a position farther from the seatingsurface portion of the seat cushion, than a position of the secondheater portion, and wherein the control unit controls, if the physiqueof the occupant detected by the physique detector is smaller than thestandard, such that an output of the sub-heater is made smaller in orderof the first heater portion, the second heater portion, and the thirdheater portion.
 15. The seat according to claim 14, wherein thesub-heater is disposed on left and right sides of the main heater, andwherein the first heater portion, the second heater portion, and thethird heater portion are disposed side-by-side in this order from aninner side to an outer side in the leftward-rightward direction.
 16. Theseat according to claim 10, wherein the main heater includes a cushionmain-heater which is disposed on the seating surface portion of the seatcushion, and a back main-heater which is disposed on a seating surfaceportion of a seat back, wherein the sub-heater includes a cushionsub-heater which is disposed on left and right outer sides of theseating surface portion of the seat cushion, and a back sub-heater whichis disposed on left and right outer sides of the seating surface portionof the seat back, and wherein the control unit stops the electric powersupply to the back sub-heater if the physique of the occupant detectedby the physique detector is smaller than a first standard, and stops theelectric power supply to the back sub-heater and the cushion sub-heaterif the physique of the occupant detected by the physique detector issmaller than a second standard which is smaller than the first standard.17. The seat according to claim 10, wherein the main heater is providedto the seating surface portion of the seat, and wherein the sub-heateris provided to a bulging portion which is disposed on left and rightouter sides of the seating surface portion, and which juts out towardthe occupant for supporting a side portion of the occupant.